Remove checking on double.

- All conversions among floating point types should be allowed.

Change-Id: I6223bece51f5b2a535ab3369c5c4380f18acc74d


[ROCm/hip commit: 094ff5431e]

projects/hip/include/hip/amd_detail/hip_fp16.h

@@ -220,9 +220,7 @@ THE SOFTWARE.
             #if !defined(__HIP_NO_HALF_CONVERSIONS__)
                 template<
                     typename T,
-                    Enable_if_t<
-                        std::is_floating_point<T>{} &&
-                        !std::is_same<T, double>{}>* = nullptr>
+                    Enable_if_t<std::is_floating_point<T>{}>* = nullptr>
                 __host__ __device__
                 operator T() const { return data; }
             #endif